Science explained with humor, analogy, and pop culture. (Because sometimes you just wanna understand a thing…)

Rainbow Animals (Part 1): The Violet Myth

Are There Rainbow Animals?

Rainbow animals! Not just for your child’s fridge drawings anymore! It happens, and way more often than you might think.

When I say “rainbow animal” what do you think of? A random sampling of nearby humans mostly said ‘macaw’ and the ever vague, “I don’t know, fish?”

Would you believe: lizard, coral, beetle, tree? …I have such awesome photos for you…

Define ‘Rainbow Colored’

But wait, what counts as rainbow colored? At first, I was adamant that any rainbow-colored animal must include the color purple. And so I rejected the macaw based on its totally unwarranted boycott on purple. Not that they aren’t amazing, but a line must be drawn, and I’m choosing Harold to draw it.

However, it turns out I should forget about purple, because, as I discovered, purple is not a color of the rainbow. What? What is this purple poppycosh? This vocal violet vandalism??

Why Purple Dissed the Rainbow

Here’s the reasoning: When Isaac Newton split light into its colors with a prism, he labelled them:

Newton fail. He also spent hours trying to decode the prophesies in the Bible, so you know, win some, lose some.

Red, Orange, Yellow, Green, Blue, Indigo, and Violet (ROYGBIV). Apparently he only included “indigo” so that the number of color names would match the western musical scale (do rey me fa so la ti).

We think that’s sort of dumb and irrelevant now, and so we ignore indigo because physicists have nothing to prove to musicians. Also, “indigo” sounds so pretentious and doesn’t deserve a whole category of blueness equivalent to a giant, simple category like Red. Notice we don’t include “currant” or “garnet.”

So okay, throw out indigo. Rainbows are still red, orange, yellow, green, blue, and violet. Yeah, violet, as in purple, right? Wrong. Back in Isaac’s day “blue” meant light blue, like cyan or sky blue, and “violet” actually meant dark blue, like in the navy.

Therefore, there is no purple in the rainbow. (In other news, there is no Santa Claus!)

Roses are red, violets are blue, this song proves nothing, I blame you…Crayon.

This whole violet thing is misrepresented ALL THE TIME in diagrams and everyday items in catalogs. It’s very understandable that I, I mean, you, might have been confused.

But I’ve Seen Purple in a Rainbow!

And yet- the next time you see a rainbow, you might notice that that last ring is definitely purple, not this weak sauce, dark blue that is no substitute. Why? You might say. WHY?! You’re not crazy, you are in fact seeing purple. Let’s break it down…

Red wavelengths are stretchy outey, blue are shorty short

Rainbow Basics: Rainbows result when the light travels through a raindrop, bends, and then reflects back out at an angle off the back of the drop. (That’s why the sun is always behind you if you can see a rainbow).

Each wavelength bends slightly differently than the other because of their different lengths, and that’s why we can see each color now separated into a rainbow.

Interesting Fact: we can only see one color per droplet, because each color is beaming out at different angles, and our eyes are only in one place. (mind = poof)

Rainbows’ Dark (purple) Secret

Because of constructive interference, raindrops are actually creating multiple rainbows: one bright outer one that we see, then very light inner ones, called supernumerary bows. When the raindrops in the air are just the right size and uniformity, we can actually just barely see the second rainbow overlapping onto the first, red onto blue. And what do red and blue make? Purple.

Whatever, I say rainbow animals still have to include purple. The macaw counts ONLY IF a second macaw flies underneath the first, overlapping its feathers and appearing purple to the human passerby.

Supernumerary bow where you can see the overlap even further, showing purple but also pink and light green

Glad we got the rules cleared up. But wait, did you know that the blue of an animal is not actually blue? So, should that count? To be continued…